Heater assembly with anchoring legs

ABSTRACT

The invention relates to a heater assembly for generating an inhalable aerosol. The heater assembly comprises an electrically insulating element and an electrical resistive heater. The heater comprises a central heating portion, which is configured to be heated. The heater further comprises electrical contacts, which contact the central heating portion and which are configured to supply electrical energy to the central heating portion. The heater further comprises anchoring legs, which are configured bendable. The anchoring legs are arranged adjacent to the central heating portion and configured to mechanically anchor the electrical resistive heater to the electrically insulating element. The anchoring legs are configured forming a chamfer for guiding insertion of an aerosol-generating article.

The present invention relates to a heater assembly for anaerosol-generating device for generating an inhalable aerosol.

Aerosol-generating devices are known which are configured to heataerosol-forming substrate contained in an aerosol-generating article.The article is inserted into a heating chamber, in which an electricalresistive heater is arranged. The heater heats the aerosol-formingsubstrate to volatilize the substrate. Volatilized substrate isentrained in an air flow through an airflow channel of the device andthe generated aerosol is delivered to a user.

The conventional electrical resistive heater may be provided as anexternal heater surrounding the aerosol-generating article beinginserted into the heating chamber of the device.

It would be desirable to have a heater assembly with an electricalresistive heater which is easy to manufacture, which uniformly heatsaerosol-forming substrate and which is well insulated from furthercomponents of the device.

According to a first aspect of the invention there is provided a heaterassembly for generating an inhalable aerosol. The heater assemblycomprises an electrically insulating element and an electrical resistiveheater. The heater comprises a central heating portion, which isconfigured to be heated. The heater further comprises electricalcontacts, which contact the central heating portion and which areconfigured to supply electrical energy to the central heating portion.The heater further comprises anchoring legs, which are configuredbendable. The anchoring legs are arranged adjacent to the centralheating portion and configured to mechanically anchor or mount theelectrical resistive heater to the electrically insulating element.

The electrical resistive heater will in the following also be referredto as ‘heater’. The heater according to the invention comprises thecentral heating portion for heating purposes. The central heatingportion may be arranged in the aerosol-generating device in or adjacenta heating chamber of the aerosol-generating device. In the heatingchamber, an aerosol-generating article containing aerosol-formingsubstrate may be inserted. The aerosol-generating device together withthe aerosol-generating article is referred to as aerosol-generatingsystem.

The central heating portion may be arranged such that primarily theaerosol-forming substrate of an inserted aerosol-generating article isheated. The central heating portion may for this purpose be connected tothe electrical contacts. The electrical contacts may supply electricalcurrent to the central heating portion. The current runs through thecentral heating portion thereby heating the central heating portion.

Also part of the heater are anchoring legs. In conventional heaters, theheater must be fixed to the aerosol-generating device, which may incurcomplex solutions and relative high costs. In the present invention, theheater itself provides elements for anchoring the heater. These elementsare the anchoring legs. The anchoring legs may extend from the centralheating portion. The anchoring of the anchoring legs may be realized byanchoring the legs at least partly to the electrically insulatingelement.

The heater assembly of the present invention achieves optimized heatingof the aerosol-generating article as well as good thermal insulation sothat the heating of the article is efficient and power consumption isdecreased, allowing several sessions without the need of recharging.

The central heating portion and the anchoring legs may be integrallyformed. Ease of manufacture may thus be achieved, while providing acentral heating portion for heating and anchoring legs for anchoring theheater.

The central heating portion and the anchoring legs may be configured asan integral metal sheet. The metal sheet comprising the central heatingportion as well as the anchoring legs may be made using mass productiontechnologies like etching, laser cutting or stamping. The heater maythus be simple and cheap to manufacture as mass production processes canbe used.

The integral metal sheet may have a thickness of between 50 μm and 200μm, preferably 75 μm and 150 μm, and more preferably around 100 μm. Dueto the thickness of the heater, the heater may have a low thermalinertia and may thus quickly reach its efficient heating temperature.The central heating portion may have a heating surface of between 50mm×40 mm, preferably between 35 mm×25 mm, more preferably between 20mm×15 mm.

The heater may be thus be made of an optimized low volume of a sheet ofone single material. The central heating portion and the anchoring legsmay comprise, preferably consist, of stainless steel or titanium,preferably stainless steel 304. Such materials are not toxic, do notneed relevant maintenance, and are resistant to heat and corrosive gasthat could be generated in aerosol-generating devices.

The central heating portion may have a tubular shape. The assembly ofthe heater may require only bending of the initial sheet.

The heater may be configured as an external heater positioned around aperimeter of the heating chamber. The external heater may take anysuitable form. Instead of a bend metal sheet, for example, the externalheater may take the form of one or more flexible heating foils on adielectric substrate, such as polyimide. The flexible heating foils maybe shaped to conform to the perimeter of the heating chamber.Alternatively, the external heater may take the form of a metallic gridor grids, a flexible printed circuit board, a moulded interconnectdevice (MID), ceramic heater, flexible carbon fibre heater or may beformed using a coating technique, such as plasma vapour deposition, on asuitable shaped substrate. The external heater may also be formed usinga metal having a defined relationship between temperature andresistivity. In such an exemplary device, the metal may be formed as atrack between two layers of suitable insulating materials. An externalheater formed in this manner may be used to both heat and monitor thetemperature of the external heater during operation. Preferably,however, the external heater of the present invention is made from asingle metal sheet which is bent to have a tubular shape enablingexternal heating.

The air pressure due to external heating of the aerosol-generatingarticle may push the generated aerosol to flow towards the inside of theaerosol-generating article. Inside of the aerosol-generating article,efficient air paths going to a user's mouth are typically present.Furthermore, external heating, because addressing more surface of theaerosol-generating article than internal heating, may help avoiding therisk of overheating the aerosol-generating article while increasinghomogeneous heating the substrate contained in the aerosol-generatingarticle.

The anchoring legs may comprise proximal anchoring legs and distalanchoring legs, wherein the proximal anchoring legs may be arrangedadjacent to a proximal end of the central heating portion, wherein thedistal anchoring legs may be arranged adjacent to a distal end of thecentral heating portion opposite the proximal end of the central heatingportion. The proximal anchoring legs may also be denoted as topanchoring legs and are provided downstream of the distal anchoring legs,which may also be denoted as upstream anchoring legs.

As used herein, the terms ‘upstream’, ‘downstream’, ‘proximal’,‘distal’, are used to describe the relative positions of components, orportions of components, of the aerosol-generating system in relation tothe direction in which a user draws on the aerosol-generating systemduring use thereof.

The aerosol-generating system may comprise a mouth end through which inuse an aerosol exits the aerosol-generating system and is delivered to auser. The mouth end may be a proximal end of an aerosol-generatedarticle inserted into the heating chamber of the aerosol-generatingdevice. The mouth end may thus also be referred to as the proximal end.In use, a user draws on the proximal or mouth end of theaerosol-generating system in order to inhale an aerosol generated by theaerosol-generating system. The aerosol-generating system comprises adistal end opposite the proximal or mouth end. The proximal or mouth endof the aerosol-generating system may also be referred to as thedownstream end and the distal end of the aerosol-generating system mayalso be referred to as the upstream end. Components, or portions ofcomponents, of the aerosol-generating system may be described as beingupstream or downstream of one another based on their relative positionsbetween the proximal, downstream or mouth end and the distal or upstreamend of the aerosol-generating system.

The tubular heater is preferably arranged parallel to the centrallongitudinal axis of the aerosol-generating device, which extends fromthe proximal end to the distal end or vice versa. This axis ispreferably identical to the central longitudinal axis of the electricalresistive heater.

The anchoring legs may have a longitudinal shape and may extend at leastpartially parallel to the central longitudinal axis of the electricalresistive heater. The proximal anchoring legs may extend from theproximal end of the central heating portion in a proximal or downstreamdirection. The distal anchoring legs may extend from the distal end ofthe central heating portion in a distal or upstream direction.

The electrically insulating element may have a tubular shape. Theanchoring legs may be arranged bend away from the central longitudinalaxis of the electrical resistive heater. The anchoring legs may beconfigured to bend around and hook to at least a tubular opening of theelectrically insulating element. Preferably, the proximal anchoring legsare configured being hooked to the proximal end, i.e. the proximaltubular opening, of the electrically insulating element. Preferably, thedistal anchoring legs are configured being hooked to the distal end,i.e. the distal tubular opening, of the electrically insulating element.

The anchoring legs may be bent so as to hook to the outside of thetubular electrically insulating element inside of which the centralheating portion of the heater is then arranged. The heater as well asthe electrically insulating element may thus have a tubular shape,wherein the mechanical connection between the tubular electricallyinsulating element and the tubular central heating portion is realizedby the outwardly bent anchoring legs. The term ‘tubular’ regarding theheater is thus to be understood as the central heating portion of theheater having a tubular shape. The anchoring legs may bend outwards tohook the tubular electrically insulating element, while thisconfiguration is still encompassed by the term of a ‘tubular shapedheater’.

Because the legs, which are arranged outside of the tubular electricallyinsulating element, are not heated to a relevant degree, theelectrically insulating element acts as a thermal insulating tube forthermally insulating the central heating portion relative to the furthercomponents of the aerosol-generating device.

The proximal tubular opening of the electrically insulating element maybe arranged adjacent to the proximal end of the central heating portion.The distal tubular opening of the electrically insulating element may bearranged opposite the proximal tubular opening of the electricallyinsulating element and adjacent to the distal end of the central heatingportion. In other words, the tubular electrically insulating element mayessentially cover the tubular central heating portion, while theanchoring legs extend over the tubular electrically insulating elementso that the anchoring legs can be bent around the openings of thetubular electrically insulating element to securely anchor the tubularheater to the tubular electrically insulating element.

The anchoring legs may extend from the proximal and the distal ends ofthe central heating portion. The anchoring legs may not be provided onside portions of the central heating portion, which run along thelongitudinal axis of the aerosol-generating device. The anchoring legsmay be configured to prevent unwanted displacement of the heater alongthe longitudinal axis of the aerosol-generating device during insertionand removal of an aerosol-generating article.

The anchoring legs may be indirectly connected to the electricalcontacts. In other words, the anchoring legs may be electricallyconnected to the central heating portion, but not part of a conductivepath which runs from a first electrical contact through the centralheating portion towards a second electrical contact. The anchoring legsmay thus be configured in an ‘open circuit’, i.e. the heating currentused in the central heating portion for resistance heating does not runinto them, and so the anchoring legs are not heated by resistanceheating as it is the case for the central heating portion.

Heat may then only travel into the anchoring legs by conductive heatingwhich will provide low heating energy in comparison to the heat providedin the central heating portion by resistance heating. The heat in theanchoring legs will furthermore decrease along the anchoring legslength, so the ends of the anchoring legs will be much colder than thecentral heating portion. The anchoring legs may thus be used foranchoring the heater without significant heat loss and without unwantedheating of other components of the aerosol-generating device.

The electrically insulating element may be made from electricallyinsulating material, preferably made from polyether ether ketone (PEEK),and preferably may be made from thermally insulating material. Theinsulating tube may thus be made from a thermal and electricalinsulating material, like PEEK for instance, e.g. a material that isthermostable and both electrically and thermally insulating. PEEK is aspecies within the family of polyarylether ketones (PAEK). One or moresuitable materials may be utilized, including, but are not limited to,aluminium, polyether ether ketone (PEEK), polyimides, such as Kapton®,polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP),polystyrene (PS), fluorinated ethylene propylene (FEP),polytetrafluoroethylene (PTFE), epoxy resins, polyurethane resins andvinyl resins. The thermal insulation may protect the other part of theaerosol-generating device, as well as the user, from the heat of theheater. Secure connection between the electrical resistive heater andthe electrically insulating element may also lead to prevention of heathazards due to thermal insulation of the heater.

The electrical insulation facilitates that the anchoring legs used tohook the heater to the electrically insulating element may not be incontact with electrical conductor material to prevent current fromrunning through the anchoring legs and thus to prevent heating of theanchoring legs.

The electrically insulating element may surround the heater so that theheater may be uniformly anchored to the electrically insulating element.At least one, preferably both, of the heater and the electricallyinsulating element may partly or fully surround the heating chamber ofthe aerosol-generating device. Preferably, the heater and theelectrically insulating element fully surround the heating chamber ofthe aerosol-generating device.

The electrically insulating element may further comprise a firstring-shaped element and a second ring shaped element, wherein the firstring-shaped element may be configured to mechanically attach theproximal anchoring legs to the proximal tubular opening of theelectrically insulating element. The second ring-shaped element may beconfigured to mechanically attach the distal anchoring legs to thedistal tubular opening of the electrically insulating element oppositethe proximal tubular opening of the electrically insulating element.

The rings may be provided for securing the hooking connection betweenthe heater and the electrically insulating element. The rings may clampthe anchoring legs to the electrically insulating element. The clampingof the anchoring legs to the electrically insulating element may be donemechanically, for example by a press fit. Thus, glue may not be neededso that the resulting element consisting of the heater, the electricallyinsulating element and the rings has a strong stability and thus anoptimized lifespan, without the risk of having glue losing its gluingproperty due to the aerosol or heat generated by the heater.Alternatively, glue may be used instead or in addition to the mechanicalconnection between the heater and the electrically insulating element.

The rings may comprise connection elements to facilitate a secureconnection between the rings and the anchoring legs as well as theelectrically insulating element. For example, the rings may compriseprotruding elements or recesses matching corresponding elements providedon the outer surface of the electrically insulating element. Thesematching elements may be provided to facilitate a snap fit between therings and the electrically insulating element, thereby sandwiching andhence securing the anchoring legs between the rings and the electricallyinsulating element. The connection elements may be provided flexible.Only one ring may be provided on the proximal or distal end of theelectrically insulating element if sufficient for securing the heater tothe electrically insulating element. Consequently, anchoring legs mayonly be provided on one end of the central heating region if sufficientfor securely holding the heater.

The rings preferably comprise a cavity for enabling through-flow of airand aerosol. The rings may be made from electrically and thermallyinsulating material such as PEEK.

The anchoring legs may be configured forming a chamfer for guiding anaerosol-generating article during insertion into the heating chamber.Once bent and hooking the electrically insulating element, the legs maythus provide slopes for guiding an aerosol-generating article towardsthe center of the heater, helping the insertion of an aerosol-generatingarticle by the user. In other words, the anchoring legs form a funneleasing insertion of an aerosol-generating article. Again in other words,the anchoring legs, in the area where the article has to be inserted,are arranged along the hyperbolas of the upper surface of a one-sheethyperboloid of revolution, so they run from a wide to a narrower tubularpart, helping guiding the user to easily insert the article into thecenter of the heater.

The central heating portion may comprise a non-linear conductive pathbetween the electrical contacts. The central heating portion maycomprise a zigzag conductive path between the electrical contacts. Theconductive path between the electrical contacts may be optimized forheat generating. The conductive path may run over essentially the wholesurface of the central heating portion to facilitate uniform heating.The conductive path may be realized by incisions in the metal sheet ofthe heater. The incisions may be provided in a direction parallel to thecentral longitudinal axis of the aerosol-generating device. Instead oradditional to incision, recessed may be provided in the central heatingportion.

The central heating portion may comprise multiple conductive pathsbetween corresponding pairs of individually controllable electricalcontacts. The conductive paths may be provided electrically insulatedfrom each other. Different regions of aerosol-forming substrate may beheated by providing multiple conductive paths. In this regard, theaerosol-generating device may comprise a controller for controlling theheating of the multiple conductive paths. A conductive path may beheated during one puff of a user, thereby depleting an adjacent regionof aerosol-forming substrate of an inserted aerosol-generating article.

The controller may be a simple switch. Alternatively the controller maybe electric circuitry and may comprise one or more microprocessors ormicrocontrollers. The microprocessor may be a programmablemicroprocessor. The controller may comprise further electroniccomponents. The controller may be configured to regulate a supply ofpower to the heater or to individual conductive paths of the heater.Power may be supplied to the heater continuously following activation ofthe device or may be supplied intermittently, such as on a puff-by-puffbasis. The power may be supplied to the heater in the form of pulses ofelectrical current. The controller may be configured to monitor theelectrical resistance of the heater, and preferably to control thesupply of power to the heater dependent on the electrical resistance ofthe heater. The controller may be configured to progressively heat theaerosol-forming substrate, for example by adjusting the voltage to theelectrical contacts of the heater, or the number of electrical pathsactivated or by using pulse-width modulation (PWM).

The controller may be connected to a puff detection system.Alternatively, the activation may be triggered by pressing an on-offbutton, held for the duration of the user's puff.

The puff detection system may be provided as a sensor, which may beconfigured as an airflow sensor and may measure the airflow rate. Theairflow rate is a parameter characterizing the amount of air that isdrawn through the airflow path of the aerosol-generating device per timeby the user. The initiation of the puff may be detected by the airflowsensor when the airflow exceeds a predetermined threshold. Initiationmay also be detected upon a user activating a button.

The sensor may also be configured as a pressure sensor to measure thepressure of the air inside the aerosol-generating device which is drawnthrough the airflow path of the device by the user during a puff. Thesensor may be configured to measure a pressure difference or pressuredrop between the pressure of ambient air outside of theaerosol-generating device and of the air which is drawn through thedevice by the user. The pressure of the air may be detected at an airinlet, preferably a semi-open inlet, at a proximal end of the device, atthe heating chamber or at any other passage or chamber within theaerosol-generating device, through which the air flows. When the userdraws on the aerosol-generating system, a negative pressure or vacuum iscreated inside the device, wherein the negative pressure may be detectedby the pressure sensor. The term ‘negative pressure’ is to be understoodas a relative pressure with respect to the pressure of ambient air. Inother words, when the user draws on the system, the air which is drawnthrough the device has a pressure which is lower than the pressure offambient air outside of the device. The initiation of the puff may bedetected by the pressure sensor if the pressure difference exceeds apredetermined threshold.

The central heating portion may be configured stretchable. This featuremay be realized by the recesses or incisions used for creating thenon-linear conductive path between the electrical contacts. The centralheating portion may utilize the flexibility of the metal material fromwhich the central heating portion is made to enable amending thediameter or circumference of the tubular heater. If desired, theamendable diameter may be used to securely hold an insertedaerosol-generating article in the heating chamber by a friction fitbetween the central heating portion of the heater and the insertedaerosol-generating article. Generally, at least the central heatingportion may facilitate an efficient confinement for anaerosol-generating article.

The central heating portion of the heater may have a diametercorresponding to the diameter of an inserted aerosol-generating articleso that the article is securely held in the heating chamber. Thestretchability of the central heating portion may be utilized toincrease the retention force acting upon an inserted aerosol-generatingarticle. In this regard, the diameter of an article may be slightlylarger than the diameter of the tubular central heating portion of theheater. During insertion of the aerosol-generating article, the centralheating portion may be slightly expanded thereby holding the article ina friction fit. The fit ensures contact between the article and theheater. The fit provides some resistance against movement of thecorresponding article along the longitudinal axis of theaerosol-generating device. An air gap between article and heater maycause thermal losses, reducing efficiency of heating of an article.Generated aerosol may be lost via an air gap. An air gap may adverselyaffect resistance to draw (RTD) of the system. Advantageously, proximityor contact between an article and the heater reduces or eliminates anair gap, increasing thermal contact, which reduces thermal losses andchances of losing aerosol through the air gap and RTD is maintainedwithin a desirable range.

The central heating portion may comprise opposing end portions, whereinthe opposing end portions may be connectable so that the central heatingportion may have a tubular shape. The opposing end portions preferablyare side portion connecting the proximal end of the central heatingportion with the distal end of the central heating portion.

The central heating portion may comprise a conductive path having aV-shape, which may be configured to penetrate aerosol-forming substratecontained in an aerosol-generating article during insertion of theaerosol-generating article into the heating chamber of theaerosol-generating device.

This additional portion of the central heating portion may be providedwith an additional conductive path independent of the initial conductivepath of the central heating portion. The conductive path of the V-shapedadditional portion of the central heating portion may also be part of asingle conductive path of the central heating portion. The V-shapedadditional portion is preferably provided as an internal heater, whilethe rest of the central heating portion surrounds an insertedaerosol-generating article thus constituting an external heater. TheV-shaped additional portion may optimize uniform heating of theaerosol-forming substrate contained in the aerosol-generating articledue to the fact that the aerosol-forming substrate is heated from theinside as well as from the outside according to this aspect.

The aerosol-generating device may comprise a power supply for supplyingpower to the heater. The power supply may be controlled by thecontroller. The power supply may be any suitable power supply, forexample a DC voltage source such as a battery. In one embodiment, thepower supply is a Lithium-ion battery. Alternatively, the power supplymay be a Nickel-metal hydride battery, a Nickel cadmium battery, or aLithium based battery, for example a Lithium-Cobalt, aLithium-Iron-Phosphate, Lithium Titanate or a Lithium-Polymer battery.

As used herein, an ‘aerosol-generating device’ relates to a device thatinteracts with an aerosol-forming substrate to generate an aerosol. Theaerosol-forming substrate may be part of an aerosol-generating article,for example part of a smoking article. An aerosol-generating device maybe a smoking device that interacts with an aerosol-forming substrate ofan aerosol-generating article to generate an aerosol that is directlyinhalable into a user's lungs thorough the user's mouth. Anaerosol-generating device may be a holder. Apart from the heaterassembly itself, the present invention is also directed to anaerosol-generating device comprising a heater assembly as describedabove.

The device is preferably a portable or handheld device that iscomfortable to hold between the fingers of a single hand. The device maybe substantially cylindrical in shape and has a length of between 70 and120 mm. The maximum diameter of the device is preferably between 10 and20 mm. In one embodiment the device has a polygonal cross section andhas a protruding button formed on one face. In this embodiment, thediameter of the device is between 12.7 and 13.65 mm taken from a flatface to an opposing flat face; between 13.4 and 14.2 mm taken from anedge to an opposing edge (i.e., from the intersection of two faces onone side of the device to a corresponding intersection on the otherside), and between 14.2 and 15 mm taken from a top of the button to anopposing bottom flat face. The device may be an electrically heatedsmoking device.

In another aspect of the invention, there is provided anaerosol-generating system comprising an aerosol-generating device with aheater assembly as described herein and one or more aerosol-generatingarticles configured to be received in the heating chamber of theaerosol-generating device. During operation, an aerosol-generatingarticle containing the aerosol-forming substrate may be partiallycontained within the aerosol-generating device.

The aerosol-generating system is a combination of an aerosol-generatingdevice and one or more aerosol-generating articles for use with thedevice. However, the aerosol-generating system may include additionalcomponents, such as for example a charging unit for recharging anon-board electric power supply in an electrically operated or electricaerosol-generating device.

As used herein, the term ‘aerosol-generating article’ refers to anarticle comprising an aerosol-forming substrate that is capable ofreleasing volatile compounds that can form an aerosol. For example, anaerosol-generating article may be a smoking article that generates anaerosol that is directly inhalable into a user's lung through the user'smouth. An aerosol-generating article may be disposable. A smokingarticle comprising an aerosol-forming substrate comprising tobacco isreferred to as a tobacco stick.

The aerosol-generating article may be substantially cylindrical inshape. The aerosol-generating article may be substantially elongate. Theaerosol-generating article may have a length and a circumferencesubstantially perpendicular to the length. The aerosol-forming substratemay be substantially cylindrical in shape. The aerosol-forming substratemay be substantially elongate. The aerosol-forming substrate may alsohave a length and a circumference substantially perpendicular to thelength.

The aerosol-generating article may have a total length betweenapproximately 30 mm and approximately 100 mm. The aerosol-generatingarticle may have an external diameter between approximately 5 mm andapproximately 12 mm. Preferably, the aerosol-generating article has adiameter of between 5 mm and 8 mm. More preferably, theaerosol-generating article has a diameter of around 5.4 mm or 7.8 mm.The aerosol-generating article may comprise a filter plug. The filterplug may be located at a downstream end of the aerosol-generatingarticle. The filter plug may be a cellulose acetate filter plug. Thefilter plug is approximately 7 mm in length in one embodiment, but mayhave a length of between approximately 5 mm to approximately 10 mm.

In one embodiment, the aerosol-generating article has a total length ofapproximately 45 mm. The aerosol-generating article may have an externaldiameter of approximately 7.2 mm. Further, the aerosol-forming substratemay have a length of approximately 10 mm. Alternatively, theaerosol-forming substrate may have a length of approximately 12 mm.Further, the diameter of the aerosol-forming substrate may be betweenapproximately 5 mm and approximately 12 mm. The aerosol-generatingarticle may comprise an outer paper wrapper. Further, theaerosol-generating article may comprise a separation between theaerosol-forming substrate and the filter plug. The separation may beapproximately 18 mm, but may be in the range of approximately 5 mm toapproximately 25 mm.

As used herein, the term ‘aerosol-forming substrate’ relates to asubstrate capable of releasing volatile compounds that can form anaerosol. Such volatile compounds may be released by heating theaerosol-forming substrate. An aerosol-forming substrate may convenientlybe part of an aerosol-generating article or smoking article.

The aerosol-forming substrate may be a solid aerosol-forming substrate.Alternatively, the aerosol-forming substrate may comprise both solid andliquid components. The aerosol-forming substrate may be provided in theform of a gel. The aerosol-forming substrate may comprise atobacco-containing material containing volatile tobacco flavourcompounds which are released from the substrate upon heating.Alternatively, the aerosol-forming substrate may comprise a non-tobaccomaterial. The aerosol-forming substrate may further comprise an aerosolformer that facilitates the formation of a dense and stable aerosol.Examples of suitable aerosol formers are glycerine and propylene glycol.

If the aerosol-forming substrate is a solid aerosol-forming substrate,the solid aerosol-forming substrate may comprise, for example, one ormore of: powder, granules, pellets, shreds, spaghettis, strips or sheetscontaining one or more of: herb leaf, tobacco leaf, fragments of tobaccoribs, reconstituted tobacco, homogenised tobacco, extruded tobacco, castleaf tobacco and expanded tobacco. The solid aerosol-forming substratemay be in loose form, or may be provided in a suitable container orcartridge. Optionally, the solid aerosol-forming substrate may containadditional tobacco or non-tobacco volatile flavour compounds, to bereleased upon heating of the substrate. The solid aerosol-formingsubstrate may also contain capsules that, for example, include theadditional tobacco or non-tobacco volatile flavour compounds and suchcapsules may melt during heating of the solid aerosol-forming substrate.

As used herein, homogenised tobacco refers to material formed byagglomerating particulate tobacco. Homogenised tobacco may be in theform of a sheet. Homogenised tobacco material may have an aerosol-formercontent of greater than 5% on a dry weight basis. Homogenised tobaccomaterial may alternatively have an aerosol former content of between 5%and 30% by weight on a dry weight basis. Sheets of homogenised tobaccomaterial may be formed by agglomerating particulate tobacco obtained bygrinding or otherwise combining one or both of tobacco leaf lamina andtobacco leaf stems. Alternatively, or in addition, sheets of homogenisedtobacco material may comprise one or more of tobacco dust, tobacco finesand other particulate tobacco by-products formed during, for example,the treating, handling and shipping of tobacco. Sheets of homogenisedtobacco material may comprise one or more intrinsic binders, that istobacco endogenous binders, one or more extrinsic binders, that istobacco exogenous binders, or a combination thereof to help agglomeratethe particulate tobacco; alternatively, or in addition, sheets ofhomogenised tobacco material may comprise other additives including, butnot limited to, tobacco and non-tobacco fibres, aerosol-formers,humectants, plasticisers, flavourants, fillers, aqueous and non-aqueoussolvents and combinations thereof.

Optionally, the solid aerosol-forming substrate may be provided on orembedded in a thermally stable carrier. The carrier may take the form ofpowder, granules, pellets, shreds, spaghettis, strips or sheets.Alternatively, the carrier may be a tubular carrier having a thin layerof the solid substrate deposited on its inner surface, or on its outersurface, or on both its inner and outer surfaces. Such a tubular carriermay be formed of, for example, a paper, or paper like material, anon-woven carbon fibre mat, a low mass open mesh metallic screen, or aperforated metallic foil or any other thermally stable polymer matrix.

In a particularly preferred embodiment, the aerosol-forming substratecomprises a gathered crimpled sheet of homogenised tobacco material. Asused herein, the term ‘crimped sheet’ denotes a sheet having a pluralityof substantially parallel ridges or corrugations. Preferably, when theaerosol-generating article has been assembled, the substantiallyparallel ridges or corrugations extend along or parallel to thelongitudinal axis of the aerosol-generating article. This advantageouslyfacilitates gathering of the crimped sheet of homogenised tobaccomaterial to form the aerosol-forming substrate. However, it will beappreciated that crimped sheets of homogenised tobacco material forinclusion in the aerosol-generating article may alternatively or inaddition have a plurality of substantially parallel ridges orcorrugations that are disposed at an acute or obtuse angle to thelongitudinal axis of the aerosol-generating article when theaerosol-generating article has been assembled. In certain embodiments,the aerosol-forming substrate may comprise a gathered sheet ofhomogenised tobacco material that is substantially evenly textured oversubstantially its entire surface. For example, the aerosol-formingsubstrate may comprise a gathered crimped sheet of homogenised tobaccomaterial comprising a plurality of substantially parallel ridges orcorrugations that are substantially evenly spaced-apart across the widthof the sheet.

The solid aerosol-forming substrate may be deposited on the surface ofthe carrier in the form of, for example, a sheet, foam, gel or slurry.The solid aerosol-forming substrate may be deposited on the entiresurface of the carrier, or alternatively, may be deposited in a patternin order to provide a non-uniform flavour delivery during use.

The portion of the heater, which is in contact with the aerosol-formingsubstrate, is heated as a result of the electrical current passingthrough the heater. The current is supplied by a power supply. Thisportion of the heater may be configured to reach a temperature ofbetween about 140° C. and about 340° C. in use. Preferably, the heatermay be configured to reach a temperature of between about 140° C. andabout 250° C. More preferably, the heater may be configured to reach atemperature of between about 140° C. and about 200° C., most preferablyof between about 140° C. and about 160° C. A low heater temperature mayprevent overheating of the surrounding housing of the device therebypreventing discomfort for a user. Energy may additionally be saved,thereby preserving battery power. Low heater temperatures mayadditionally reduce or avoid formation of undesired constituents duringheating of the aerosol-forming substrate.

The invention further relates to a method for manufacturing a heaterassembly, wherein the method comprises the steps of:

i) providing an electrically insulating element,

ii) providing an electrical resistive heater, the heater comprising:

-   -   a central heating portion, which is configured to be heated,    -   electrical contacts, which contact the central heating portion        and which are configured to supply electrical energy to the        central heating portion, and    -   anchoring legs, which are configured bendable, wherein the        anchoring legs are arranged adjacent to the central heating        portion,

iii) adapting the central heating portion so that the central heatingportion has a tubular shape,

iv) inserting the central heating portion into the electricallyinsulating element, and

v) bending the anchoring legs outwards and at least partially around theelectrically insulating element to anchor the electrical resistiveheater to the electrically insulating element.

Features described in relation to one aspect may equally be applied toother aspects of the invention.

The invention will be further described, by way of example only, withreference to the accompanying drawings in which:

FIG. 1 shows illustrative aspects of a heater assembly of the presentinvention,

FIG. 2 shows an exploded view of the heater assembly together with anelectrically insulating element and rings for attachment,

FIG. 3 shows the components shown in FIG. 2 assembled together as wellas an aerosol-generating article to be inserted, and

FIG. 4 shows a heat image of the heater assembly.

FIG. 1 shows two aspects of the electrical resistive heater comprising acentral heating portion 10. Electrically connected with the centralheating portion 10 are a first electrical contact 12 and a secondelectrical contact 14. The electrical contacts 12, 14 are provided forsupplying electrical energy from a power supply such as a batterytowards the heater.

In both aspects shown in FIG. 1, the heater is provided as a flat sheetof metal. As will be described in more detail below, the flat metalsheet is subsequently bent so that the heater then has a tubular shape.In addition to the central heating portion 10 and the electricalcontacts 12, 14, the heater comprises anchoring legs 16. The anchoringlegs 16 are integrally formed from the same metal sheet as the centralheating portion 10. The anchoring legs 16 are provided on opposing endsof the central heating portion 10. The side portions of the centralheating portion 10 connecting the opposing ends of the central heatingportion 10 are configured to be connected with each other so that thetubular shape of the heater can be realized.

In the left and right aspects of the heater, different configurationsfor creating a conductive path in the central heating portion 10 areshown. The conductive path preferably is a zigzag path for enablinguniform heating of the central heating portion 10.

FIG. 2 shows further components of the aerosol-generating device. Theheater is also depicted in FIG. 2. However, the heater has in FIG. 2been brought in the tubular shape by bending the metal sheet. The upperpart in FIG. 2 is a proximal direction of the device, while the lowerpart of FIG. 2 is a distal direction of the device. This means that airflows from the lower upstream part towards the upper downstream part.The anchoring legs 16 can in FIG. 2 be seen to be provided at proximaland distal ends of the tubular heater.

Further depicted in FIG. 2 is an electrically resistive element 18 whichis made from thermally and electrically insulating material such asPEEK. The electrically resistive element 18 is provided for surroundingthe heater and thereby electrically and thermally insulating the heaterfrom further components of the aerosol-generating device. Theelectrically resistive element 18 also comprises a proximal end 20 and adistal end 22. The anchoring legs 16 are configured to bend outwards andover the ends 20, 22 of the electrically resistive element 18 to anchorthe heater to the electrically resistive element 18.

For securely holding the anchoring legs 16 in place, a proximal ring 24and a distal ring 26 are provided. The rings 24, 26 are configured toclamp the anchoring legs 16 between the rings 24, 26 and theelectrically resistive element 18.

FIG. 3 shows the components introduced in FIG. 2 in an assembled state.In this figure, the central heating portion 10 is arranged inside of theelectrically resistive element 18. The central heating portion 10 andthe electrically resistive element 18 both have a tubular shape andsurround a heating chamber of the aerosol-generating device into which aconsumable in the form on an aerosol-generating article 28 can beinserted. Due to the central heating portion 10 being arranged on theinside of the electrically resistive element 18, the central heatingportion 10 comes into direct contact with the aerosol-generating article28 so that aerosol-forming substrate contained in the aerosol-generatingarticle 28 can be optimally heated. By surrounding the central heatingportion 10 with the thermally insulating electrically resistive element18, heat is trapped inside of the heating chamber, thereby optimizingenergy efficiency of the device.

FIG. 3 also shows that the anchoring legs 16 are bend outwards andaround the proximal end 20 and the distal end 22 of the electricallyresistive element 18. For securing the anchoring legs 16 in place andthus securing the central heating portion 10 in the desired positioninside of the electrically resistive element 18, the rings 24, 26 areshown in FIG. 3 clamping the anchoring legs 16. The whole elementconsisting of the central heating portion 10, the anchoring legs 16, theelectrically resistive element 18 and the rings 24, 26 thus constitutesan element being configured to provide a space into which theaerosol-generating article 28 can be inserted and which is configuredfor heating the article 28 while being electrically and thermallyinsulated with respect to the rest of the aerosol-generating device.

Additionally, it is shown in FIG. 3 that the bend anchoring legs 16constitute a chamfer 30 for facilitating insertion of theaerosol-generating article 28 into the heating chamber of theaerosol-generating device.

FIG. 4 shows a heat image of the heater assembly. It can be seen thatthe heating predominantly takes place in the central heating portion 10.This is due to the fact that the conductive path runs from the firstelectrical contact 12 through the central heating portion 10 and towardsthe second electrical contact 14 (or vice versa). The anchoring legs 16do not participate in this conductive path and are therefore onlypassively heated by conduction of heat from the central heating portion10 to the anchoring legs 16. After bending of the anchoring legs 16around the end portions 20, 22 of the electrically resistive element 18,the ends of the anchoring legs 16 are negligibly heated. In other words,the ends of the anchoring legs 16 being arranged on the outside of theelectrically resistive element 18 in comparison with the rest of theheater assembly, mainly the central heating portion 10, being arrangedon the inside of the electrically resistive element 18 do not radiaterelevant amounts of heat to the outside of the heating chamber. Hence, aheater is provided from a single sheet of metal material whichconstitutes not only the heating portion of the heater, i.e. the centralheating portion 10, but also the fixation means of the heater, i.e. theanchoring legs 16, while at the same time optimizing electrical andthermal insulation and stability of the heater.

1. A heater assembly for aerosol-generating device for generating aninhalable aerosol, the heater assembly comprising: an electricallyinsulating element, and an electrical resistive heater, the heatercomprising: a central heating portion, which is configured to be heated,electrical contacts, which contact the central heating portion and whichare configured to supply electrical energy to the central heatingportion, and anchoring legs, which are configured bendable, wherein theanchoring legs are arranged adjacent to the central heating portion andconfigured to mechanically anchor the electrical resistive heater to theelectrically insulating element, and wherein the anchoring legs areconfigured forming a chamfer for guiding insertion of anaerosol-generating article.
 2. The heater assembly according to claim 1,wherein the central heating portion and the anchoring legs areintegrally formed.
 3. The heater assembly according to claim 1, whereinthe central heating portion and the anchoring legs are configured as anintegral metal sheet.
 4. The heater assembly according to claim 1,wherein the central heating portion has a tubular shape.
 5. The heaterassembly according to claim 1, wherein the anchoring legs compriseproximal anchoring legs and distal anchoring legs, wherein the proximalanchoring legs are arranged adjacent to and extending from a proximalend of the central heating portion, and wherein the distal anchoringlegs are arranged adjacent to and extending from a distal end of thecentral heating portion opposite the proximal end of the central heatingportion.
 6. The heater assembly to claim 1, wherein the anchoring legsare arranged bend away from the central longitudinal axis of theelectrical resistive heater.
 7. The heater assembly according to claim1, wherein the anchoring legs have a longitudinal shape and preferablyextend at least partially parallel to the central longitudinal axis ofthe electrical resistive heater.
 8. The heater assembly according toclaim 1, wherein the electrically insulating element has a tubularshape.
 9. The heater assembly according to claim 8, wherein theanchoring legs are configured to bend around and hook to at least aproximal tubular opening of the electrically insulating element.
 10. Theheater assembly according to claim 9, wherein the anchoring legscomprise proximal anchoring legs, wherein the proximal anchoring legsare arranged adjacent to and extending from a proximal end of thecentral heating portion and are configured to bend around and hook tothe proximal tubular opening of the electrically insulating element, theproximal tubular opening of the electrically insulating element beingarranged adjacent to the proximal end of the central heating portion,and wherein the anchoring legs comprise distal anchoring legs, whereinthe distal anchoring legs are arranged adjacent to and extending from adistal end of the central heating portion opposite the proximal end ofthe central heating portion and are configured to bend around and hookto a distal tubular opening of the electrically insulating element, thedistal tubular opening of the electrically insulating element beingarranged opposite the proximal tubular opening of the electricallyinsulating element and adjacent to the distal end of the central heatingportion.
 11. The heater assembly according to claim 1, wherein theelectrically insulating element further comprises a first ring-shapedelement and a second ring shaped element, wherein the first ring-shapedelement is configured to mechanically attach the anchoring legs to aproximal tubular opening of the electrically insulating element, andwherein the second ring-shaped element is configured to mechanicallyattach the anchoring legs to a distal tubular opening of theelectrically insulating element opposite the proximal tubular opening ofthe electrically insulating element.
 12. The heater assembly accordingto claim 1, wherein the electrical resistive heater is configuredsurrounding a heating chamber of an associated aerosol-generatingdevice, and wherein the heating chamber is configured for receiving theaerosol-generating article containing aerosol-forming substrate.
 13. Theheater assembly according to claim 12, wherein the chamfer of theanchoring legs is configured for guiding insertion of theaerosol-generating article into the heating chamber.
 14. The heaterassembly according to claim 1, wherein the central heating portioncomprises opposing end portions, and wherein the opposing end portionsare connectable so that the central heating portion has a tubular shape.15. A method for manufacturing a heater assembly, wherein the methodcomprises the steps of: i) providing an electrically insulating element,ii) providing an electrical resistive heater, the heater comprising: acentral heating portion, which is configured to be heated, electricalcontacts, which contact the central heating portion and which areconfigured to supply electrical energy to the central heating portion,and anchoring legs, which are configured bendable, wherein the anchoringlegs are arranged adjacent to the central heating portion, and whereinthe anchoring legs are configured forming a chamfer for guidinginsertion of an aerosol-generating article, iii) adapting the centralheating portion so that the central heating portion has a tubular shape,iv) inserting the central heating portion into the electricallyinsulating element, and v) bending the anchoring legs outwards and atleast partially around the electrically insulating element to anchor theelectrical resistive heater to the electrically insulating element.